1. Field of the Invention
The present invention relates to a display apparatus, information processing apparatus, image display system, display apparatus control method and information processing apparatus control method.
2. Description of the Related Art
Recently, presentations in a conference, workshop, and the like often use a projector which projects an image signal received from a personal computer (to be referred to as PC) on the screen.
In general, a PC and projector send/receive image signals via an analog connection using an analog RGB cable. However, the analog connection is cumbersome, a connection from a remote place is difficult, and there is a need to simultaneously connect a plurality of PCs. For these reasons, an image display system which connects a PC and projector via a communication line is receiving attention.
Conventionally, to implement an image display system, a screen displayed on the monitor of an information processing apparatus such as a PC is periodically captured, and the captured image data is sent to a display apparatus such as a projector.
Note that screen capturing is for obtaining, by a driver from a video memory, screen data displayed on the monitor of a PC or the like, and temporarily storing it in an internal RAM.
When a projector is connected to a plurality of PCs via a communication line, one projector can display the screens of these PCs side by side (to be referred to as multi-screen display). Similarly, one projector can display a plurality of screen data such as the primary and secondary screens of one PC by multi-screen display.
For example, Japanese Patent Laid-Open No. 2004-054134 discloses a technique capable of multi-screen display to display the display screens of a plurality of communicably connected terminal devices on one screen of a display apparatus. A communication unit receives captured image data sent from each terminal device having the screen capturing function. An image composition unit composites the respective captured image data into image data of one screen by screen division. A display control unit implements multi-screen display.
However, in Japanese Patent Laid-Open No. 2004-054134, multi-screen display is done in the same way regardless of the monitor screens of different PCs which display images irrelevant to each other on their monitors, or a plurality of monitor screens of one PC. In display of respective screens close to each other, visibility becomes poor when different monitor screens irrelevant to each other are seen. If respective screens are displayed apart from each other, a plurality of relevant monitor screens for one PC are hardly recognized as one original continuous image, degrading visibility.